(Reuters) - An Alaska glacier is exposing remains from a military air tragedy six decades later.Relics from an Air Force cargo plane that slammed into a mountain in November 1952, killing all 52 servicemen on board, first emerged last summer on Colony Glacier, about 50 miles east of Anchorage.That discovery, by Alaska National Guard crews flying training missions out of Anchorage, put into motion a sophisticated recovery program carried out by the Hawaii-based Joint POW/MIA Accounting Command.After last year's initial work - when nearly everything that rose to the glacier's surface was picked up - the JPAC team came back this summer to collect additional relics pushed out of the ice since then.